Résumé

Recent evidence strongly suggests that natural selection can favour the evolution of consistent individual differences in behaviour ('personalities'). Indeed, personality shows heritable variation and has been linked to fitness in many species. However, the fitness effects of personality are highly variable within and between species. Furthermore, the nature of the causal influence of personality on an organism's fitness remains unclear so far. Competition has been proposed as a factor modulating this relationship. Thus, personality has been found to affect individual success in competition by interference in a few species, but its influence in scramble competition remains unexplored. We assessed exploratory tendencies (thought to be a key component of personality) in a model species, the zebra finch, Taeniopygia guttata. In a first session, we formed foraging flocks composed of four individuals with different exploration scores, and allowed them to play producer-scrounger games repeatedly. During a second session, individuals were reassigned to different flocks to check for consistency in the influence of exploratory tendency across different social contexts. Exploratory tendency influenced individual feeding success during the first session but not during the second one. High-exploratory birds were less successful at finding food (i.e. playing the producer tactic) and consequently had a lower feeding success, but were presumably able to adjust their behaviour between sessions. We discuss our results in relation to the interactive effects of both personality and experience, and highlight the role of competition processes on the evolution of personality.